My newest and best one is TRAINS
I think I'm becoming a train spotter. I caught myself thinking about how much I want to go see the 19.50 sleeper train from Fort William to London Euston train when it gets to Westerton, just for the thrill of seeing the Deerstalker I didn't know passed so near to where I live, yet not to a major Glasgow station (until a few days ago when fiddling about on NRE). And the abbreviation for Fort Willaim is FTW!
I've found myself wanting to know all about the engineering and infrastructure of trains and lines I've been on. Hanging out at stations, reading timetables and making hypothetical journeys on NRE, watching programmes about railway history and disused lines, Trains are mint, keeping all my tickets, any trivia or stories involving trains and OMG model railway! If I ever have enough money, I'm going to devote a whole room in my house to trains.
I'm hoping to get a week long pass all around Scotland in April. Going over the Forth Bridge is like the best thing ever. Then inter-rail in Europe in the summer :D